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Stag beetle mouthparts

The mouthparts of the adult the stag beetles are: the mandibles, the maxillae, the labrum and the labium. The mandibles are adapted for combat/defence and the maxillae and labium for lapping up liquids.
Below is a close-up of a side view of a male Lucanus cervus head. The female mouth parts are just the same, except for the smaller mandibles.

Male stag beetle enjoying a ripe juicy melon, MF 2003.

Mouthparts of a male stag beetle drinking from a ripe melon. Photo by Maria Fremlin, 8 June 2003.

Their mouth has a clear bilateral symmetry. Both the maxillae and labium have sensory palps with which the beetles taste their food. Note that only the right palp of the labium is visible.
The galea is the maxillar part adapted for licking, it is covered with the bristles. The labium also has a part adapted for licking which is hidden to us when viewing the beetle from above. It sits just below the galea.

In order to see their mouthparts even better, below is a magnified view of their dissection *.

Maxilla and labium of Lucanus cervus

Dissected maxillae and labium of Lucanus cervus. Courtesy of Professor Harald Krenn.

The ligula (Li) is the labial part adapted for licking. It is covered with bristles like the galea (Ga).
The names of the other parts are the following. Starting with the maxilla: cardo (Ca), stipes (St), maxillar palp (Mxp) and lacinia (Lc); the maxillar lobe is not marked. It is the oval part below the stipes. For the labium: paramentum (Pr), labial palp (Lp) and ligula (Li).

The function of the bristles in both the galea and the ligula is to mop-up the liquids by capillary action, which is the only way that stag beetles may take some nourishment. The stag beetles move them in and out of their mouths while they do so. For example, this female stag beetle is drinking maple syrup just like that.
These parts are quite stiff as well, so they can be easily plunged into soft fruits. This can be clearly seen on a video of a stag beetle feeding on a plum.

* This image came in the following paper: Krenn, H.W., Pernstich A., Messner T., Hannappel U., Paulus H.F. (2002)  Kirschen als Nahrung des männlichen Hirschkäfers, Lucanus cervus (Linnaeus 1758) (Lucanidae: Coleoptera). Entomologische Zeitschrift 112/6: 165-170. [PDF]

Acknowledgement: I'm very grateful to Professor Harald Krenn for sharing with the website the diagram of the dissected mouthparts of Lucanus cervus.

For examples of other insect mouthparts, click here
Do Yellow-bellied Sapsuckers Really Suck Sap? - Apparently they also lap it up!

Last modified: Thurs Feb 20 2014

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